Drill.



M. L. HANLIN &.' E. B. ROSS.

DRILL. APPLICATION FILED JULY 15, 1910.

Patentd Mar.28, 1911.

shank, as shown, since they are readily smoothed ofi flush with thesurface of the shank when thedrill is finished. The shank is now readyto receive the drill, which is inserted in the groove 14, its upper endabutting against the pin 15, as shown in Fig. l, and its side edgesfitting tightly in the groove 14, as shown in Fig. 8. When the parts areassembled in the manner described, spaces 16 remain at opposite sides ofthe drill, as shown in Fig. 8. The parts are then secured. togetherpermanently by brazing, the bracing compound being applied. to thegrooves and engaging surfaces of the drill and socket. The drill is thenheated to fuse the brazing compound which runs along the points ofcontact of the surfaces and firmly unites the drill with the shank andalso firmly secures the pin 15 in place. The drill is then ready forfinishing, which consists in smoothing the ends of the pin 15 andpolishing the surfaces.

It will be seen that by proceeding in the manner described the drillproper is fixedly secured in the socket and is brazed thereto so that itcannotflbecome displaced, and this is accomplished without cuttingentirely through the shank transversely as has heretofore been thepractice. We thus preserve the strength of the original materialcomposing theshank and render unnecessary the application to the-shankof a strengthening hoop or band, as has heretofore been neces sary inorder to secure the requisite strength I to prevent the-drill frombecoming loosened by the severe twisting strains to which it issubjected. As a matter of fact, the securing of the drill inplaoe bysuch bands is not satisfactory as they are apt to stretch and the drillsoon becomes loosened. Furthermore, by providing the spaces 16 by ourim' proved method of construction the contacting surfaces of the drilland shank are comparatively restricted in area, a considerable 7 portionof the surface of the drill being out -of contact with the shank. Thisis an important advantage as, owing to the unequal expansion andcontraction of the two kinds of metal used, it is desirable that thecontacting surfaces be as limited as possible as otherwise they are aptto become loosened.

It will be understood that the term drill as herein employed is used ina generic sense and is intended to comprehend not only! drills, strictlyspeaking, but also reamers and, other analogous tools.

That which we claim as ourinvention, and

desire to'secure by Letters Patent, is, I

1. A cutting or boring tool, comprising a shank having a recess in itslower end provided with grooves to receive the. edges of a drill, anda'drill fitted in said grooves and fixedly secured to the shank.

.2. A cutting or boring tool, comprising a shank having a recess in itslower end provided with grooves to receive the edges of a drill, a plugsecured in the shank and extending transversely through the innerportion of said recess, and a drill fitted in said grooves and fixedlysecured to the shank.

3. A cutting or boring tool, comprising a shank having a cylindricalrecess in its lower end provided with groovesat its sides to re ceivethe edges of a drill, and a drill substantially rectangular incross-section fitted in said grooves.

4:. A composite drill composed of a shank and a drill having diflerentcoefficients of expansion, said shank havin a recess of greater diameterthan the thickness of the drill and having grooves to receive the edgestogether.

MERTON L. HAMLIN. EDWIN B. RGSS. Witnesses.

Ammo F. Howe, Crrannns F. PEARS.

